Ceramic bodies having internal honeycomb structures defined by porous walls have several uses, e.g., as particulate filter bodies. Such uses require selected channels of the structure to be sealed or plugged at one or both of the respective ends of the filter body.
In the operation of a ceramic plugged filter, a contaminated fluid or gas is brought under pressure to an inlet face and enters the ceramic filter body via those channels with open ends at the inlet face. Because these channels are sealed at the opposite (outlet) face, the contaminated fluid is forced through the thin porous walls into adjoining channels. The solid particulate contaminant in the fluid, which is too large to pass through the porous openings in the walls, is left behind, and a cleansed fluid exits the filter through the outlet channels.
Sealing the channels involves inserting a plugging material into the open ends of select channels, and subsequently drying the plugged filter. Plugging methods can potentially lead to defects, such as holes or fissures, in the plugs, which cause filter leaks. The channel walls of the honeycomb structure can contain defects, such as holes or fissures. It is therefore important in the filter manufacturing process to be able to quickly and efficiently inspect the ceramic filter bodies for defects that could ultimately cause leaks in the subsequently formed filter.